Three dimensional large screen movie techniques employing holography and a cylindrical optical system

ABSTRACT

Holographic information-processing techniques which result in a hologram being formed on photosensitive material capable of reconstructing an image in real space many times the size of the hologram. Horizontal and vertical information components of an object scene to be holographically recorded are treated independently of each other. The horizontal informational component is reduced by an optical system and recorded across a long dimension of a rectangular hologram. In a preferred form of the invention, the horizontal informational component is dispersed prior to holographic recordation in order to reduce the bandwidth of said information. Except for the possible use of light-gathering optics, the vertical informational component of an object scene to be recorded along the narrow dimension of the hologram is not processed. Successive holograms so constructed are placed on a film and drawn across their narrow direction through a shutterless continuous wave coherent light beam to reconstruct in real space successive images that appear to a theater audience to form continuous action. The horizontal information component is displayed in full three dimensions while the vertical information is projected with limited three dimensionality to each member of the audience from the hologram through a lenticular screen.

- United States Patent [7 21 Inventor Daniel S. St. John I-lockessln,Del.

[21 Appl. No. 1,603

[22] Filed Jan. 9, 1970 [45] Patented Dec. 7, 1971 [73] Assigneel-lolotron Corporation [54] 'IIIREE DIMENSIONAL LARGE SCREEN MOVIETECHNIQUES EMPLOYING I'IOLOGRAPI'IY AND A CYLINDRICAL OPTICAL SYSTEM 162SF, 127, 128; l78/6.5, 6.8; 352/85, 86

[56] References Cited UNITED STATES PATENTS 3,498,690 3/1970 Tyler350/35 3,5l4,l77 5/1970 Lohmann 350/35 OTHER REFERENCES Kock et al,Proc. ofthe IEEE, Jan. 1967, pp. 79- 81 De Bitetto, Applied Optics, Vol.8, No. 8, Aug. 1969, pp. l740- 1741 Primary Examiner- David SchonbergAssistant Examiner-R. .l. Stern ,Anorney-Woodcock, Washburn, Kurtz andMackiewicz ABSTRACT: Holographic information-processing techniques whichresult in a hologram being formed on photosensitive material capable ofreconstructing an image in real space many times the size of thehologram. Horizontal and vertical information components of an objectscene to be holographically recorded are treated independently of eachother. The horizontal informational component is reduced by an opticalsystem and recorded across a long dimension of a rectangular hologram.In a preferred form of the invention, the horizontal informationalcomponent is dispersed prior to holographic recordation in order toreduce the bandwidth of said information. Except for the possible use oflight-gathering optics, the vertical informational component of anobject scene to be recorded along the narrow dimension of the hologramis not processed. Successive holograms so constructed are placed on afilm and drawn across their narrow direction through a shutterlesscontinuous wave coherent light beam to reconstruct in real spacesuccessive images that appear to a theater audience to form continuousaction. The horizontal information component is displayed in full threedimensions while the vertical information is projected with limitedthree dimensionality to each member of the audience from the hologramthrough a lenticular screen.

PATENTED nEc 71am 35255 4 sum 1 or 6 PATENTEU DEC 7 I97! SHEET 2 [IF 6PATENTED uEc nan SHEET 3 OF 6 PATENTEU on: '7 |97i sum MP 6 PATENIED um7 I971 SHEET 5 BF 6 I63 LASER IIIIIIIJIIIJI/lllIJIIIIIIII1 OBJECT SHEET6 [IF 6 THREE DIMENSION-AL LARGE SCREEN MOVIE TECHNIQUES EMPLOYINGHOLOGRAPHY AND A CYLINDRICAL OPTICAL SYSTEM BACKGROUND OF THE INVENTIONThis invention relates generally to improvements in the techniques ofoptical holography and more specifically to improved holographictechniques for recording and reconstructing three-dimensional theatersize and quality moving pictures.

Ofi-axis holography is described generally by Leith and Upatnieks in theScientific American June, 1965, pages 25-35, and in their copendingpatent application Ser. No. 361,977, filed Apr. 23, 1964, issued Apr.14, 1970 as U.S. Pat. No. 3,506,327. Briefly described, the generaltechnique of off-axis holography includes directing a coherent lightbeam toward an object and thence as an object-modified beam onto aphotosensitive holographic detector such as photographic film. Areference beam coherent with the object-illuminating beam isalso'tiirected at the photosensitive detector at some finite angle withthe object-modified beam for interference therewith at the hologramdetector. Recorded on the detector is an interference pattern whichcarries both phase and intensity information of the object-modifiedlight beam wave front. When illuminated with a coherent light beamsimilar to the reference beam used during its construction, at least onefirst order beam is diffracted by the hologram interference pattern thatcarries an image of the object in full three dimensions which may beviewed by an observer positioning himself within the diffracted beam.

It has naturally been suggested that these techniques of holography maybe utilized to make a movie capable of reconstructing a large screentheater size moving picture in full three dimensions which may be viewedwithout the aid of Polaroid glasses or some other apparatus. However,use of these basic holographic techniques along to construct such amovie present enormous technical problems. Primarily, the size of eachhologram frame of a multihologram movie must be larger than thereconstructed image size desired in order to provide the large viewingangle necessary for good threedimensional reconstruction.

There have recently been certain advances in holographic data reductiontechniques which allows reducing the size of each individual hologramwithout reducing the size of the reconstructed image or its viewingangle. One such technique utilizes a dispersion medium in theobject-modified beam between the object and the photosensitive detectorduring the construction of a hologram. This is described by Kenneth A.Haines in the Proceedings of the IEEE, Aug. 1967, pages l,5121,513, inApplied Optics, Vol. 7, pages 1,l851,189, June 1968) as well as in acopending patent application Ser. No. 809,171, filed Mar. 21, 1969, andanother copending application Ser. No. 875,768 filed on Nov. 12, 1969.Such data reduction without loss of image size or viewing angle isaccomplished at the expense of decreased image resolution or increasednoise or both.

The data reduction techniques described therein do not allow reductionof the hologram size sufficiently in all directions to make practical alarge screen movie of a significant length. Therefore, it is a primaryobject of this invention to provide a method and apparatus foradditionally reducing the size of a hologram.

Among other objects of the present invention is to provide a holographicmovie technique capable of reconstructing a continuous image for viewingby an audience of many people with a three-dimensional representation ofthe object scene holographically recorded.

SUMMARY OF THE INVENTION These and additional objects are accomplishedby the improved techniques according to this invention which includeconstructing a hologram and reconstructing an image therefrom bytreating the vertical aspect of an object scene independently of itshorizontal aspect. In constructing a hologram according to thisinvention, information of the horizontal aspect of an object scenerecorded is compressed into a hologram aperture having a horizontaldimension much less than the horizontal extent of the object scenerecorded and the image thereof to be eventually reconstructed from thehologram.

Two techniques are alternatively utilized for providing this informationreduction of the horizontal aspects of the objectmodified light beamwithout loss of the reconstructed-image viewing angle. (The term viewingangle" as used herein refers to the angular extent, as subtended from areconstructed image of an object, of positions from which substantiallyall of the image may be viewed.) One of these techniques utilizescylindrical optics to compress the horizontal component of anobject-modified light beam into the hologram aperture in the nature of ahorizontally focused image hologram. A second technique combines suchhorizontal light gathering with dispersion of the object-modified lightbeam rays in horizontal planes by use of a two-dimensional dispersionmedium placed therein. The second technique has an important advantageover the first technique in allowing the horizontal dimension of thehologram aperture to be additionally reduced while maintaining a widehorizontal reconstructed image-carrying beam angle for covering a largearea and thereby playing to a large number of people.

Information of the vertical aspect of the object scene is recordedaccording to ordinary techniques of holography without data reduction.Even without data reduction, the vertical dimension of the halogramaperture is very small with respect to the vertical dimension of theobject scene being recorded and many times smaller than the horizontaldimension of the hologram aperture. The field of view of thereconstructed image in the vertical direction is sacrificed by theextremely small vertical hologram dimension used without informationreduction. However, sacrifice of the three-dimensional informationalcontent is of little consequence because of the horizontal orientationof the human eyes wherein depth is perceived primarily in the horizontalcomponent of the image, anyway. To produce a wide vertical reconstructedbeam angle for projecting the two dimensional vertical image aspect overa large area, light diffracted by a hologram is dispersed in verticalplanes by a dispersion medium, such as a lenticular screen, placedwithin a reconstructed image. The very small vertical dimension of thehologram aperture which results from sacrificing the three-dimensionalinformation of the vertical aspects of the object scene further makes itmuch easier to produce and reconstruct a holographic movie wherein anindividual hologram frame is constructed of an object scene every smallfraction of a second. The film area required to store movie informationis reduced to within manageable proportions. Also, an image isreconstructed which does not significantly move as the hologram movesrelative to its reconstructing light beam.

These techniques are applied to construction of a holographic movie byrecording the object scene several times each second upon individualholograms preferably with the use of a pulsed laser synchronized with afilm advance. Either the cylindrical optics or the combined cylindricaloptics and a horizontal dispersion medium are included in an apparatusfor making such a movie. When a master copy is completed, a plurality ofcopies are made by reconstructing an image from the master movie throughthe same cylindrical optics and/or dispersion mediums utilized in itsconstruction, thereby to eliminate the effect of any aberrations inthese optical elements. An image reconstructed in real space from eachframe of the master movie is pseudoscopic; that is, the image appears tobe wrong side out. A copy hologram is made of this image as its objectin the same way as the master movie was made and using additionalcylindrical optics and perhaps a horizontal dispersion medium. Imagesreconstructed in real space from the copy movies are orthoscopic; thatis, the image looks to the observer as if he were observing the objectscene itself.

A copy holographic movie is reconstructed in a theater by a laser sourcethat generates an effectively continuous wave coherent beam throughwhich the movie is driven at a uniform speed. By effectively" continuousis meant herein a laser beam that appears to an observer to becontinuous; this may be a continuous wave or a rapidly pulsed beam. Itis not necessary to pulse the laser or use shutters or in any other waysynchronize the film-illuminating system in a frame by frame exposure.By recording information on the hologram with its vertical aspectunfocused, reconstructed images will move only an amount as maximumwhich is equal to the vertical dimension of each hologram. Since thisdimension is very small compared to the image size, the motion isgenerally not observed by the audience. To add stability to thereconstructed image with such continuous film motion, the reference beamused in constructing the copy movie is given a radius of curvature sothat it appears to come from a point source located a distance from thehologram detector that is substantially equal to the distance of pointswithin an image of an object scene being copied and the hologramdetector.

In front of the copy film during its reconstruction and in the path ofan image-carrying diffracted beam is placed the same cylindrical optics,or the combination cylindrical optics and a dispersion medium, whichwere used to construct the copy movie. A full sized image of the objectis reconstructed in the horizontal direction with full threedimensionality. The vertical information passes through the horizontaloptics without modification and is spread out to be observable to allmembers of an audience by a lenticular screen which is oriented in amanner not to affect the horizontal information of the object scene.

If it is not desired to reconstruct a full sized image of the objectscene, the object scene may be reduced by ordinary high qualityspherical optics and this reduced image used as the object of thehologram movie.

These general aspects of the present invention as well as additionalaspects and details thereof may be better understood with reference tothe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates reconstruction of aholographic movie according to this invention in a plan view of atheater;

FIG. 1A shows an elevation view of the movie theater reconstruction ofFIG. 1;

FIG. 2 illustrates the construction of a hologram according to oneaspect of the present invention;

FIG. 3 illustrates a technique for copying a hologram constructedaccording to the technique of FIG. 2;

FIG. 4 illustrates the reconstruction of a hologram copied by thetechnique of FIG. 3;

FIG. 5 shows the construction of a hologram according to another aspectof the present invention;

FIG. 6 illustrates a technique for copying a hologram made according toFIG. 5;

FIG. 7 shows the reconstruction of a hologram copied by the methodillustrated in FIG. 6;

FIG. 8 shows an alternative method for copying a hologram constructedaccording to the techniques illustrates in FIG. 5;

FIG. 9 shows the reconstruction of a copy hologram constructed accordingto the technique of FIG. 8;

FIG. 10 illustrates a technique of constructing a hologram which is amodification of the technique illustrated in FIG. 5;

FIG. 1] demonstrates the requirements of an optical element of the typeutilized in FIGS. 5-10;

FIG. 12 shows a preferred configuration of individual holograms on ahologram movie;

FIG. 13 shows the essential elements of an apparatus for constructing aholographic movie according to the techniques of this invention;

FIG. 14 shows the construction of a hologram in a manner similar to FIG.5 but with the use of spherical optics;

FIG. 15 shows the copying of a hologram constructed according to FIG.14; and

FIG. 16 shows the reconstruction of a copy hologram formed according tothe technique of FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS To illustrate the projectionrequirements contemplated for a holographic movie according to thepresent invention, a projection system in a theater is shown in planview in FIG. 1 and in elevation view in FIG. 1A. A holographic moviefilm I1 is drawn through a coherent illumination beam 13 which isgenerated by an effectively continuous wave laser 15. Appropriateoptical elements give the coherent light beam 13 the proper light wavefront curvature, as discussed hereinafter with respect to specificexamples. The holographic movie 11 is drawn at a continuous speed from asupply reel to a takeup reel by an appropriate motor source 17. A mask19 having an aperture 21 of an area approximately equal to that of eachindividual hologram blocks a portion of the light beam 13. Each hologramdiffracts a portion of the incident light into an image-carryingdiffracted first order bean 23. The holographic movie contains aseparate hologram for each image to be reconstructed and contains enoughholograms to reconstruct a large enough number of distinct images perunit time to give the visual effect of an image with continuous motion.It should be noted, however, that no shutter is required for playing theholographic movie nor is any other device necessary to interrrupt thelight or cause the holographic movie to move intermittently, thussimplifying the reprojecting equipment.

The image-carrying diffracted first order beam 23 is processed by anappropriate optical system 25, specific examples of which are describedhereinafter. A number of theater seats, such as the seat 27, areprovided for a movie viewing audience. The number of seats that may beprovided and their arrangement depend upon the size of the reconstructedimage and also upon horizontal beam spread angle 0 of the reconstructedimage-carrying diffracted beam 29. To view the entire movie image, allpersons must sit within the area of the diffracted beam 29 within whichlight is diffracted from every exit point of the optical system 25. Inthe vertical direction, there must be a beam spread angle of 0 of thereconstructed image-carrying diffracted beam 29 so that all personssitting at various elevations may also see the entire vertical extent ofthe image. The laser 15 emits light of a single color chosen to bewithin a range acceptable for extended viewing.

To make a holographic movie, a succession of individual holograms isconstructed on an appropriate photosensitive detector, each hologramrecording the object scene at an exclusive point in time. The techniquesof this invention are not, however, limited to construction of a moviebut also include certain novel individual hologram constructiontechniques of wide application. FIG. 2 shows a method of constructing asingle hologram frame of the holographic movie according to one aspectof the present invention. Information of an object 31 is to be recordedon a photosensitive holographic detector within the hologram aperture33. The hologram aperture 33 is very much smaller than the object 31 soin order to construct a hologram capable of reconstructing a full sizeimage without loss of viewing angle in the horizontal direction,information of the horizontal aspect of the object 31 is reduced intothe hologram aperture 33 by a cylindrical optical system which mayinclude, for example, two wide aperture cylindrical lenses 35 and 37. Atemporally coherent light beam 39 from an appropriate laser source isreflected from the object 31 and its horizontal aspects are imaged intothe hologram aperture 33. A reference beam 41 of coherent light is alsodirected against the hologram aperture 33 to form an interferencepattern upon intersection with spatially reduced object-modifiedradiation 40 reflected from the object 31 for'recordation by thehologram detector. A photosensitive hologram detector is preferablyhigh-resolution silver emulsion photographic film.

It should be noted that the cylindrical optical elements 35 and 37 mustbe of very large aperture in order to gather enough light forholographic construction and also in order to give a hologram capable ofreconstructing an image of the object with a wide viewing angle.Additionally, exactly two cylindrical optical elements is notnecessarily the optimum arrangement since any particular design willdepend upon all the specific circumstances of a given application. Whatis important, according to this aspect of the invention, is thatcylindrical optics focus only the horizontal aspect of the informationof the object 31 onto the hologram aperture 33 and allow the verticalinformation to pass onto the aperture without significant alteration.

To reconstruct an image from a hologram after exposure and appropriateprocessing of the hologram detector, it is illuminated with coherentlight. An image-carrying beam is diffracted by the hologram and directedback through the same cylindrical optics used during its construction.However, an image so reconstructed in real space will be pseudoscopicwhich is often undesirable for holographic movies of most subject mattertypes. Since copies of the hologram constructed of the object aregenerally desired anyway, it is preferable to effect a conversion of thepseudoscopic image into an orthoscopic one in a copying step such asthat illustrated in FIG. 3. The original hologram 33 is illuminated witha reconstructing coherent light beam 41' which has a curvature oppositeto that of the reference beam 41 used in constructing the hologram. Thebeam 41' strikes the hologram from its opposite side. The zero-order orundiffracted light 43 comes to a point focus and is conveniently blockedby a small mask 45. An image-carrying diffracted-light beam 47 (similarto the object-modified beam 40 but a complex conjugate thereof) isdirected back through the same cylindrical lenses used in constructingthe hologram to reconstruct the initial wave front recorded. Theselenses are spaced the same distance from the hologram 33' as they werefrom the hologram aperture 33 of FIG. 2 during hologram construction ifthe same light wavelengths are employed in both the construction andreconstruction steps. Since the same lenses are used, their imagingquality need not be maintained perfect. Any aberrations of these opticalelements will be corrected upon reconstruction.

At about the location in real space where a pseudoscopic image (notshown) is brought to focus in the diffracted beam 47 of FIG. 3, acylindrical lens 49 of good imaging quality is positioned to collectlight in the vertical direction and direct it toward a copy hologramaperture 51. The lens 49 preferably does not affect the horizontalaspect of the diffracted imagecarrying beam. In the horizontaldirection, the reconstructed image is focused into hologram aperture 51by cylindrical optics which may include, for instance, a pair of lenses53 and 55 which are of wide aperture. These lenses perform the samefunction as the cylindrical lenses 35 and 37 used in making the originalhologram. A diverging reference beam 57 of FIG. 3 preferably has a wavefront curvature upon striking the hologram aperture 51 which makes itappear to have originated from a point source 59 that is located adistance from the hologram aperture 51 equal the distance between somepoints of an image (preferably in the middle thereof) reconstructed fromthe hologram 33 and the aperture 51. This is important for constructionof a holographic movie which may be shown without the use of shutters ora pulsed laser. The reference beam 57 must be coherent with thereconstructing beam 41', which beams are most easily obtained from asingle laser according to ordinary optical techniques. Furthermore, thislight is most conveniently the same wavelength as that used to constructthe hologram 33, but the cylindrical optics are insensitive to a changein wavelength.

After processing, the copy hologram 51' is illuminated as part of aholographic movie for reconstruction of an orthoscopic image 31' of theobject 31, as shown in FIG. 4. The holographic 51' is illuminated with areconstructing beam 57' which has an opposite wave front curvature thanthe reference beam 57 used in constructing the hologram. Furthermore,the

reconstructing beam 57' strikes the hologram 51' on the opposite sidefrom that which the reference beam 57 struck the hologram. Animage-carrying first order beam 61 diffracted by the hologram 51' isdirected back through the lenses 55 and 53, used in making the copy; toform an image 31 of the object 31. A lenticular screen 63 is positionedto pass through the space wherein the image 31' is formed. This screenis most conveniently made of some plastic material and has on onesurface thereof a number of cylindrical elements (lenticles) extendingin a horizontal direction and having dimensions in the verticaldimension of about 1 mm. so the audience will not clearly see them. Thelenticular screen 63 does not affect the horizontal aspect of the image.The image focused on the screen 63 is sampled by each lenticular elementand reprojected over a beam spread angle 1 that is wide enough to coverthe entire audience. This beam spread is not directly obtained in thereconstructed beam 61 diffracted by the hologram because of the verythin vertical dimension of the hologram 51' which has been constructedwithout compensation therefor by vertical information data reducingoptics such as is done with cylindrical optics in the horizontaldirection. Even with use of the lenticular screen 63, the small verticaldimension of the hologram 51' does not provide three-dimensionalinformation in the vertical direction of the image 31' but this is oflittle concern since an individuals eyes are horizontally displacedwhich results in depth perception in the horizontal dimension only. Theimage 31' as to its horizontal aspects is fully three dimensional.

When it is said that the same lenses 53 and 55 are used duringreconstruction that were used in making the copy hologram now beingviewed, it should be understood that in order to be able to show morethan one copy simultaneously in more than one theater, other lenses mustalso be useable. These lenses are preferably formed from plastic by amolding process and it can be seen that for a given mold in constructinga number of such lenses that each lens will have substantially the samecharacteristics, including aberrations, as every other. Therefore, thecylindrical lenses used in reconstructing the hologram according to FIG.4 should be constructed in the same manner as the lenses 53 and 55 usedin making a hologram copy according to FIG. 3. This approach stillresults in the ability to use lenses which are not optically perfectsince they will all have substantially the same aberrations anddistortions and those introduced during the making of a copy will beeliminated during the reconstruction through similar lenses.

As has been noted with respect to FIG. 1, the horizontal angle of spread0 determines the number of people who can view the horizontal movie.Referring again to FIG. 4, it may be observed that from ordinary opticalprinciples, the angle 0' which is the extent of the light diffracted bythe hologram 51 is related to the angle 0 by the power of magnificationof the cylindrical lenses 53 and 55. That is, the ratio of the imagewidth to the horizontal dimension of the hologram aperture is determinedby the ratio 670. It can be seen, then, that for large imageprojections, the hologram 51' must similarly have a large horizontalextension. In certain applications, this limitation is undesirable andlimits desirable data reduction. A technique without this restrictionuses a dispersive medium (scatter plate) in combination with acylindrical lens during the hologram construction for horizontal datareduction.

Referring to FIG. 5, an object 65 is illuminated with temporallycoherent light 67 and reflects an object-modified beam 69 toward ahologram aperture 71. An optical element or elements is positioned inthe path of the object-modified beam 69 and includes in tandem atwo-dimensional dispersion medium which scatters light in horizontaldirections only and a cylindrical lens which has curvature in thehorizontal direction only. This horizontal data reduction is preferablyperformed by a single optical element 73 having a dispersion medium 75on its incident surface and a cylindrical lens element 74 as part of itsexit surface. The dispersion medium 75 preferred herein includes astructure which imparts to a light wave front passing therethrough aperiodically varying phase thereacross in a horizontal direction with asubstantially zero relative phase change across the wave front in avertical direction. This result is preferably obtained by a dispersivemedium in the form of periodic ridges and grooves (corrugations) scoredinto the face of the transparent optical element 73. The ridges andgrooves occur periodically across the horizontal direction and areequally curved. The period is about 3 mm., depending on the lightwavelength and the hologram construction geometry. The curves of theridges and grooves in horizontal cross section are preferably parabolicsections in order to spread a beam of light over the desired angle withuniform intensity. Although a random ridge an groove shape is workable,it is not preferred because of the greater difficulty in realignmentupon reconstruction and because of the wider angles through which someof the light is scattered.

As described in more detail in aforementioned copending patentapplication Ser. No. 809,171 copending application Ser. No. 875,768filed Nov. 12, 1969, and in published papers of Kenneth A. I-Iaines, theuse of a dispersive medium in the path of the object-modified beambetween the object and hologram detector codes the object-modified beamin a manner that reduces the spatial frequencies that the hologram mustrecord and also reduces the hologram size necessary to recordinformation about an image with a wide angle of view. An image-carryingbeam reconstructed from the hologram carries this code, so it must bedecoded" by positioning therein a similar dispersive structure. Thefield of view of a decoded reconstructed image is the same as if thehologram detector had been placed in a plane of the dispersive mediumand with its two-dimensional size. Of course, these principles areapplied herein only to the horizontal aspect of the object informationand the vertical aspect is unaffected by use of the dispersion mediumherein.

The cylindrical lens portion of the optical element 73 bends dispersedobject-modified light into the hologram aperture 71 for interferencewith a reference beam 77. The reference beam preferably has a wave frontcurvature to make this appear to have originated from a point source 79substantially the same distance from the hologram aperture 71 as thatdistance between the aperture and the dispersive medium 75. Use of thispreferred reference beam wave front curvature makes it easier to realignthe optical element 73 when making a hologram copy.

Referring to FIG. 6, a method of making a copy of the hologram 71 isshown. The hologram is illuminated with a reconstructing light beam 77'of opposite curvature as the reference beam 77 and striking the hologramfrom the side thereof opposite to the side exposed during itsconstruction. The hologram diffracts a portion of the reconstructinglight into a diffracted beam 79 which carries the image information. Thediffracted beam is passed back through the optical element 73 locatedthe same distance from the hologram 71' as it was located with respectto the hologram aperture 71 of FIG. 5. An image of the object is therebyreconstructed in substantially the same location relative to the opticalelement 73 as the object 65 was so located during the construction ofthe hologram. A cylindrical lens 81 of FIG. 6 is placed approximately atthis image location for gathering the light in the vertical directionand directing it toward a copy hologram aperture 83. Another combinationdispersion medium cylindrical lens optical element 85 modifies the lightin the horizontal direction only before striking the hologram aperture83.

The preferred reference beam for illuminating the hologram aperture 83of FIG. 6 is one with a complex wave front curvature that appears tohave originated fonn both a vertical line 87 and a horizontal line 89.The line 87 is located a distance from the aperture 83 which issubstantially the same as the distance between dispersive corrugationsof the lens 85 and the aperture 83. The horizontal line 89 is located adistance from the aperture 83 that is substantially equal to thedistance between object points of the pseudoscopic image reconstructedfrom the hologram 71' and the aperture 83. Such a reference beam may beobtained by a number of specific optical combinations, one of whichmight utilize a point or apparent point source 91 located between thereconstructed pseudoscopic image and the optical element with acylindrical lens 93 also located therebetween. A negative lens 95 isthen placed in the light beam between the optical element 85 and thehologram aperture 83. This arrangement allows both for continuous filmtransport during movie reconstruction without significant image movementand also simplifies the problem of repositioning the cylindrical opticalelement 85 during reconstruction.

Referring to FIG. 7, a technique for reconstructing images from the copyhologram 83 is illustrated. A reconstructing light beam 97 is directedagainst the hologram 83' and has a wave front curvature which is theopposite of that of the reference beam which was used in constructingthe hologram at the aperture 83. The reconstructing light beam 97 isgiven a complex wave front shape corresponding to that of the referencebeam utilized in constructing the hologram. The reconstructing beam 97is given a curvature to form a vertical focused line 99 and a horizontalfocused line 101. An imagecarrying beam 103 diffracted by the hologram83' is directed back through the cylindrical optical element 85 to forman image 65 of the object 65. In order to increase the vertical spreadof the image-carrying beam 103, a lenticular screen 105 having smallhorizontal cylindrical elements is positioned within the space occupiedby the object image 65'. The cylindrical elements of the lenticularscreen 105 should not affect the horizontal component of the imageinformation and additionally should be small enough (about 1 mm.) sothat the screen is not itself visible to the audience.

The holographic construction, copying and reconstruction techniquesdiscussed with respect to FIGS. 5-7, respectively, have the advantagethat larger images with wider viewing angles may be reconstructed from agiven hologram size than in the methods described with respect to FIGS.2-4. However, the methods of FIGS. 5-7 have a disadvantage that thecylindrical optical elements 73 and 85 must be carefully realignedduring the copying and image reconstruction steps so that thecorrugations making up the dispersive mediums are nearly exactly linedup with an image reconstructed thereof. This is not a seriousdisadvantage, however, if the corrugations 75 are periodically varyingwith a period of the order of a millimeter since realignment is not toodifficult. Additionally, the techniques described with respect to FIGS.5-7 require that the reconstructing light wavelength be more exactlythat used in constructing the hologram if the same cylindrical opticalelement used in constructing the hologram is to be used in reading itout.

Another disadvantage of the techniques illustrated with respect to FIGS.5-7 is that the copy hologram 83' which is necessary to allowreconstruction of an orthoscopic image of the object, has beenconstructed with two dispersion mediums, one on each of the cylindricaloptical members 73 and 85. Use of a dispersive medium is essentially asampling process which throws away part of the image information. Whenthis is done twice in series, an amount of information is lost that is amultiple of that information lost with a singlescatter plate. Toeliminate this double sampling, and alternative to the copyingconfiguration of FIG. 6 is to make a holographic copy capable ofreprojecting the conjugate of the wave front projected by the originalhologram just prior to leaving the scatter plate into the air. Such atechnique is illustrated in FIG. 8 wherein the master hologram 71' isilluminated with a reconstructing beam 77' and an image-carryingdiffracted beam 79 directed back through the cylindrical optical element73, much as the initial steps of making a copy according to thetechnique illustrated in FIG. 6. In the specific embodiment of FIG. 8,the cylindrical lens element 73 is mated with a second cylindrical lenselement 107 which has light-dispersing corrugations that perfectly matchthose of the cylindrical lens element 73. When the two cylindrical lenselements 73 and 107 are joined with a liquid gate therebetween to reducelight reflections, the combination performs merely like a cylindricallens, N o ima'gesampling is accomplished by the combination. A copyhologram aperture l09' receives the image-carrying diffracted beam 79after passing-through the cylindrical lens element'com'bination. Anadditional cylindri-' the opposite curvature of the reference beam 111used in" making the copy hologramiThe hologram 109' diffrac'ts a portionof the reconstructing light into an image-carrying diffracted beam 113whichis directed back through the cylindrical lens elements 10.7 andl08with the cylindrical lens element 73 removed from contact' therewithThe lens elements 107 and .108 are? positioned the same distance fromthe hologram 109 during reconstruction (FIG. 9) as they were positionedrelative to the aperture109 (FIG. 8 during construction. An orthoscopicimage 6 5 "of the object 65 is formed behind the cylindrical lenselement from the observer. The

image 65" is reconstructed with less information loss than theimage 65'reconstructed as shown in FIG. -7 In the reconstruc tion illustrated inFIG. 7, the image 65' is formed in behind the cylindrical lens element85.from the observer by a significant distance so that an.observer'focuses his eye on a location in. space removed from the noiseof the dispersive corrugations of the cylindrical lens element. Adisadvantage to the reconst'ruction illustrated inFIG. 9 is that thelenticular screen 105 is not convenientlyplaced in a location passingthrough the image 65". Placing the Ienticular screen 105 too far fromthe image results in distortions in the vertical aspect of that imagewhich cannotbe equally corrected for all locationswithin an auditoriumwherein a holographic movie'is to be displayed.

Although these disadvantages may. not be serious for some particularapplications, they 'may be corrected by making a hologram according tothe configuration of FIG. 10. The distinction over the methodillustrated with respect to FIG. is that an object 115 illuminated withcoherent light 117 is imaged into the cylindrical lens element 73through its dispersive medium 75 'by a highquality spherical optical'system, such as one including in' a telescope arrangement sphericallenses 119 and 121. These lenses must be of a very wide aperture whichmeans that-they should have a diameter of many feet in somecircumstances. An image 123 projected intothe cylindrical lens elementby the spherical lenses 119 and-121 may be demagnified if desired Thedemagnification should be only by a few times so that the depthdistortion of the image 123 by such demagnification is not so severe asto be objectionable upon reconstruction. In any event, the image 123 canbe placed wholely behind .the corrugated surface 75 of the cylindricallens element 73. A master hologram 71" is then constructed and copied inthe same manner as the hologram 71' was copied as illustrated in FIG. 8.Reconstruction of the copy hologram in the same manner as the hologram109'. is reconstructed according .to FIG. 9 places an image the samesize as the image 123 in front of the cylindrical lens element 107 sothat the lenticular screen 105 may be placed through the image so thatthe observer focuses in front of the noise plane of the dispersivecorrugations of the cylindrical element 107.

If the image 123 is focused in a position near the plane of thedispersive medium 75, certain other advantages result. The area of thedispersive medium 75 need not be so great as hereinbefore to construct ahologram capable of reconstructing an image with a given viewing angle.Additionally, a

dispersive medium is easierto reposition than in the case where theobject of the hologram is a largerdistance from the dispersive medium.

It should be noted at this point that demagnification of the objectscene into a smallerone may also be accomplished in the hologramconstruction techniques illustrated in FIGS. 2' i and 5 by the use ofhigh quality, large aperture'cylindrical optics such as the lenses 119and 121 illustrated in FIG 10. This modified technique then presents thedemagnified-object' scene as the object ofthe hologram-constructingprocess. In

reconstruction according to the techniques illustrated, the size of thereconstructed image will be the same'as the image formed for the objectof the hologram construction. That is,

the holographically reconstructed image is a demagnified, image of theoriginal object scene. Additionally, if an object image 123 is formedinor near the. dispersive corrugations 75 as shown, the area of thedispersion medium need not be so large tov maintain a given'viewingangle. Also, forming an obje ct image l23partially orl'thedispersivecorrugations 75" makesit easier to repositionthedispersivemedium upon reconstruction of the hologram. 4

Referring to FIG. 11, the characteristics desirable of a cylindricallens element utilizedin the embodiments of the invention illustratedwith respect'to FIGS. 5-10 is. shown. The cylindrical lens element 73with corrugated surface 75 is'shown in I plan view but discussionrelating thereto is equally applicable to the cylindrical lens element107 which is the mate of the lens element 73. The lens powerof thesurface 74'is chosen to be sufficient to bend a ray 125 coming from theholographic movie 127 into a point 'of the audience 129 in its middleand somewhere toward, but not jeractly at, its rear. The corrugations 75are chosen with depth and period to scatter such a light ray through anangle a. It is this requirement for placing most of the audience in thehorizontal field of view of the reconstructed image that'determines thecharacter of the cylindrical lens element used in constructing theholograms;

The lens element "73 is most easily made from plastic which has beencast in a mold carefully constructed with the desired surfaces. Y

' Alternative to the combination cylindrical Ierisa'nd dispersive mediumshown herein'is a dispersive medium alone with unequal ridges and grovesin order to perform a light bending as well as scattering function withthe bending power greatest near the edges. Such structure should have anequivalent light 7 bending and scattering capability 'asithe cylindricallens dispersive medium combination illustrated in FIG. 11.

Most of the discussion herein has dealt with construction, copying andreconstructing of a single hologram. Such a hologram is constructed manytimes each second for inclusion on a continuous length high-resolutionphotographic film in a manner such as that illustrated in FIG. 12. Thephotographic film 131 may have these individual holograms arranged 'inany number of ways but 'for relatively small size images, somewhere inthe range of 5 to lOfeet in width, it is most convenient to use aphotographic film 131 which is mm. in width and which contains a numberof narrow holograms,

such as the hologram 133 approximately 75 mm. in width and only a fewmillimeters in height. Each'hologram just touches those on either sideof it in order to prevent light flicker as the holographic movie isshown by continuous film motion. Also on such a holographic movie is asoundtrack 135 which may be a conventional movie soundtrack or oneholographically recorded according to the techniques described in acopending patent application Ser. No. 884,286, filed Dec. II, I969 byDaniel S. St. John, entitled, Continuous Holographic InformationRecording." For larger reconstructed images, a

larger individual hologram size may be necessary which thus requireseither a wider film or a rearrangement of the holograms from that shownin FIG. 12.

FIG. 13 illustrates the essential elements of a holographic movie camerafor constructing a series of holograms according to the techniqueshereinabove described. A suitable enclosure 137 contains at one endthereof the cylindrical lens element 73. An object 139 is illuminated bycoherent light 141 emitted from a diffuser 143 which is connected by anoptical path 145 to a high-powered pulsed laser 147. The optical path145 may be a series of reflective surfaces such as mirrors or a bundleof optical fibers which carry light from the laser to illumination ofthe object. The laser is supplied with power and coollant from a powersupply 149. Object-modified light 151 is directed into a hologramaperture 153 by the cylindrical lens element 73 and a second cylindricallens element 155 which affects only the vertical aspect of theobject-modified information passing therethrough. The lens 155 is anelement which has not been illustrated hereinabove but is optional as ameans for gathering light into the very small vertical dimensions of thehologram aperture. If such a lens is used, it should also be placedbetween the cylindrical lens element 73 and the master hologram formaking a copy. However, such a lens need not be included in theprojection of a copy hologram. Its advantage is to reduce somewhat theintensity with which the coherent light must illuminate an object.

The laser is pulsed at periodic intervals something in excess of timesper second and synchronized therewith is a mechanical movement (notshown) which advances a highresolution photographic film 157 an amountsomething more than the height of the hologram aperture 153 betweenlaser pulses. This combination therefore provides the necessaryshuttering effect. A reference beam 159 illuminates the hologramaperture 153, and thus the film 157, to construct a hologram. Thereference beam 159 is generated by an optical path 161 illuminating adiverging lens 163. The optical path 161 may again be optical fibers 'ora series of mirrors and should include a delay line arrangement (notshown) of some suitable design so that the light path from the lasingelement of the pulsed laser to the hologram aperture is the same throughthe reference beam light path 161 as it is through theobject-illuminating beam light path 145, to the object, and back throughthe camera optics to the hologram aperture 153. Such compensationreduces the strict requirements of temporal coherence of a suitablelaser source.

In the construction of holographic movies, the individual holograms neednot be immediately adjacent one another since in the copying processesdescribed hereinabove, each hologram is carefully positioned to becopied and may then be positioned adjacent one another as eventuallyrequired for the copy film.

It may also be noted that neither the size of the hologram nor the typeof photosensitive detector material need be the same for the originaland copy holograms. In constructing the first hologram from a real lifeobject, a fast photosensitive material is preferred because only a lowlight intensity is usually available to expose the detecting material.However, in constructing a second hologram from the first, the availablelight intensity may be made greater, thereby allowing use of a slowphotosensitive copy detecting material with better resolutioncapability.

Cylindrical optical elements are preferred to accomplish signalprocessing as described hereinbefore because they are less sensitive torepositioning in an image field than are spherical lenses. However,under certain circumstances spherical lens elements may be convenient.In FIGS. 14, and 16, spherical lenses are utilized in optical systemswhich are the counterparts, respectively, of the cylindrical systems ofFIGS. 5, 8 and 9. Referring to FIG. 14, a hologram constructiontechnique is shown which differs from that of FIG. 5 in that a scatterplate 171 and a spherical lens 173 replace the cylindrical opticalelement 73 of FIG. 5. The spherical lens 173 is positioned relative to ahologram aperture 175 so that the aperture is approximately at the focalpoint of the lens 173. This position will generally provide maximumlight reconstructed from a hologram copy to an area occupied by theaudience.

FIG. 15, the hologram 175 is illuminated with a reconstructing-lightbeam 77' which is a complex conjugate of the reference beam 77. Adiffracted beam 177 is passed back through the spherical lens 173located the same distance from the hologram 175 as it was from thehologram aperture 175 of FIG. 14. A beam 179 carrying a pseudoscopicimage 65* is passed through a flat block of optical material 181 inorder to adjust the optical path length to compensate for an omitteddispersion medium. The beam 179 then passes through another sphericallens 183 which directs light onto a second hologram aperture 185 forrecording a copy hologram 185' by interference with a reference beam187.

Referring to FIG. 16, the hologram 185 reconstructs an orthoscopic image65 of the object 65 upon illumination with a reconstructing light beam189 that is the complex conjugate of the reference beam 187 used inconstructing the hologram. The orthoscopic image 65' is formed in adiffracted beam 191 which is passed back through the lens 183 positionedthe same distance from the hologram 185' as the lens 183 was positionedfrom the hologram aperture 185 in FIG. 15. A diffracted beam is thenpassed through a dispersion medium 171* which is positioned with respectto the hologram 185' coincident with an image of the dispersion medium117, thereby to cancel out its effect. After the effect of thedispersion medium is removed, the orthoscopic image 65 becomes viewablein the diffracted beam 191 which is then passed through a lenticularscreen to spread out the image-carrying beam in a vertical direction tocover a large audience.

In all the embodiments of the present invention described herein, ahologram significantly smaller than the object scene has been recordedwhich maintains horizontally a wide angle of view of reconstructedimages having full three-dimensional characteristics. A lens ordispersion medium element is utilized for acting only on the horizontalaspect of the object scene recorded. No such element is utilized inprocessing the vertical aspect of the object information prior torecording the hologram. The vertical aspect is defocused intentionallyon a hologram aperture during construction in order to maintain allpoints of the image stationary during reconstruction, at least within adistance equal to the hologram vertical dimension, as the hologram isdrawn at a uniform velocity in its vertical direction through aneffectively continuous coherent reconstructing light beam. A wideviewing angle in the vertical direction is obtained by use of alenticular screen having cylindrical lenticles oriented in a horizontaldirection. Reconstructed image three dimensionality in a verticaldirection is lost by such a technique but this is of little concern forplaying to an audience that can detect three dimensionality primarily inthe horizontal direction.

It shall be understood that the invention is not limited to the specificarrangements shown, and that changes and modifications may be madewithin the scope of the appended claims.

What is claimed is:

I. A method of constructing a hologram, comprising the steps of:

illuminating an object scene with coherent light to produce anobject-modified wave front,

positioning to intercept the object-modified wave front an elongatedhologram detector having a horizontal dimension much greater than itsvertical dimension but many times smaller than said object scene,

processing horizontal components of the object-modified wave frontindependent of and different from its vertical components prior to saidwave front striking said detector, and

directing coherent reference radiation toward said hologram detector forinterference with the processed objectmodified wave front to generateholographic information of said object scene for recordation as ahologram.

2. The method of constructing a hologram according to claim 1 whereinsaid step of processing the horizontal components of the object-modifiedwave front includes focusing horizontal aspects of the object scene intothe horizontal dimension of the hologram detector.

3. The method according to claim 2 wherein said focusing is accomplishedby positioning cylindrical lenses in said objectmodified wave frombetween the object scene and the hologram detector.

4. A method of constructing a hologram according to claim 1 wherein thestep of processing the horizontal component of the object-modified wavefront includes dispersing rays of said wave front substantially only inhorozontal planes.

5. A method of constructing a holographic movie wherein successiveindependent holograms are constructed according to the method of clam Ialong an elongated photosensitive material. 1 K

6. A method of reconstructing an object scene image from holographicinformation recorded according to the method of claim 1, which includesthe-steps of:

generating a diffracted light order from said holographic information ina manner that allows formation of an orthoscopic image of the objectscene in real space, forming said real space orthoscopic image byprocessing horizontal components of the difiracted light order, and

dispersing light rays of said diffracted light order in vertical planesin a manner to increase the beam spread of the diffracted light order inits vertical direction.

7. A method according to claim 6 wherein the step of dispersing saidlight rays in vertical planes includes placing within said real spaceorthoscopic image a lenticular screen.

8. In a method of constructing a hologram characterized by directing toa hologram detector at a finite angle with each other for interferencethereon both an object-information-carrying light wave front and areference light wave front, the improvement comprising the steps of:

dispersing said object-information-carrying light wave front at asurface thereacross substantially only in planes extending horizontallyacross the object information wave front, and

converging said object-information-carrying light beam in a horizontaldirection onto a hologram-detecting area which has a horizontaldispersion that is at least several times smaller than the horizontalextent of said surface at which said object-information-carrying beam ishorizontally dispersed.

9. The method according to claim 8 wherein the step of dispersing theobject information wave front includes imparting to said wave front asubstantially periodic relative phase across said surface in ahorizontal direction but substantially without relative phase variationin a vertical direction thereacross.

10. The method according to claim 8 wherein the step of dispersing saidobject-information-carrying wave front includes positioning of saidsurface thereacross a refracting interface having periodically recurringpeaks and valleys across a horizontal direction thereof but withoutvariation in a vertical direction. positioning at said surfacethereacross a refracting interface having periodically recurring peaksand valleys across a horizontal direction thereof but without variationin a vertical direction.

11. The method according to claim 8 wherein the steps of dispersing andconverging said object information beam are accomplished by positioningwithin the path of said object-information-carrying light wave front alens element shaped by its surfaces to both converge and disperse saidwave front.

12. The method according to claim 8 wherein the vertical dimension ofthe hologram is many times smaller than it horizontal dimension.

13. A method of reconstructing an image from a hologram constructedaccording to claim 12, comprising the steps of:

generating from said hologram a difiracted light order wave front,

dispersing rays of said diffracted light order wave front in horizontalplanes in a manner to neutralize the coding effect of such dispersionduring construction of the hologram, and

dispersing rays of said diffracted light order wave front in verticalplanes in a manner to expand the vertical beam spread of said diffractedlight order wave front.

14. The method of reconstructing an image according to claim 13 whereinthe step of dispersing rays in vertical planes includes placing adispersion structure across said wave front at a location where anobject image comes to focus in real space, said structure accomplishingsubstantially no dispersion in horizontal planes.

15. A method of holographically reconstructing an image of an objectcomprising the steps of:

illuminating said object with coherent light to produce anobject-modified wave front,

positioning to intercept the object-modified wave front a horizontallyelongated detector many times smaller than said object,

positioning in said object-modified beam before striking said detectordata reducing optics which affect substan tially only the horizontalaspect of the object-modified wave front,

directing at said hologram a reference beam to interfere with saidhorizontally data reduced object-modified beam,

illuminating said detector with a reconstructing light wave front havinga curvature in substantially the opposite direction of the curvature ofsaid reference beam, thereby producing an image-carrying diffractedbeam, and

repositioning in said diffracted beam an optical system withsubstantially the same characteristics as said data-reducing optics in amanner to produce a pseudoscopic image of said object in real space.

16. A method according to claim 15 wherein the step of positioningdata'reducing optics includes positioning at least one cylindricaloptical surface in said object-modified beam.

17. A method according to claim 15 wherein the step of positioningdata-reducing optics includes positioning in said object-modified beam adispersion medium that scatters light in substantially horizontaldirections only.

18. A method of constructing a hologram copy of a hologram from which anobject image is reconstructed according to the method of claim 15,comprising the steps of:

positioning in said image-carrying diffracted beam a horizontallyelongated copy detector many times smaller than said object,

positioning copy-datareducing optics in said image-carrying diffractedbeam prior to striking said horizontally elongated copy detector, saidcopy-data-reducing optics affecting substantially only the horizontalaspect of the object-modified wave front, and

directing toward the copy detector a reference beam which is coherentwith said reconstruction radiation beam, thereby to construct a copy ofsaid hologram capable of reconstructing an orthoscopic image of saidobject.

19. A method of reconstructing an orthoscopic image of said object froma copy hologram constructed according to the method of claim 18,comprising the steps of:

illuminating said copy hologram with a reconstructing wave front havinga curvature opposite in direction to the curvature of said copyreference beam, thereby producing an orthoscopic image-carryingdiffracted-light beam,

positioning in said orthoscopic image-carrying diffractedlight beam onoptical system having substantially the same characteristics as saidcopy-data-reducing optics, thereby producing an orthoscopic image of theobject in real space, and

positioning in or near said orthoscopic reconstructed image a dispersionmedium characterized by a plurality of substantially cylindricalelements horizontally oriented.

20. A system of large screen holographic movie projection,

comprising,

a continuous wave laser generating a beam of coherent light,

a film transport capable of advancing a holographic movie at a uniformspeed through said coherent light beam, thereby to generate animage-carrying-diffracted beam from the movie,

a cylindrical optical system positioned relative to said laser and saidfilm transport to be located in the path of the diffracted beam andcharacterized by affecting substantially only the horizontal aspect ofsaid beam, and

a dispersion medium positioned to be located in the path of thediffracted beam and characterized by affecting substantially only thevertical aspect of said beam.

21. A system according to claim 20 wherein said dispersion mediumincludes a lenticular screen having horizontally elongated cylindricalelements.

a cylindrical lens system positioned to receive the objectmodified beamfor data reduction in the horizontal direction independent of thevertical direction.

24. A system according to claim 23 wherein said cylindrical lens systemincludes a dispersion medium for scattering rays of said object-modifiedbeam in horizontal planes.

25. A system according to claim 23 which additionally comprises acylindrical lens positioned in said object-modified beam to gather lightin the vertical direction.

29 3 33 um'ncn S'JA'II-ZS m'naw'r omen CE R '11 Fl GATE 0 if C O R R ECT! 0 N Patent No. 5 Dated December 7 1971 Daniel S. St. JohnInventor(s) It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 52, a parenthesis is missing before the word June.

Column 2 line 31, correct the spelling of the word "hologram".

Column 3, line 62, correct the spelling of the word "illustrated" Column7, line 12, delete the word "an" and insert the word -and,-

line 67 correct the spelling of the word "from" Column 8, line 60,delete the word "and" and insert the word Column 9 line 8 delete theword "lenses" and insert the word -lens-.

Column 12, line 75, correct the spelling of the word "horizontal" IN THECLARE: Column 13 line 3 correct the spelling of the word "cl.aim

line 30 delete the word "dispersion" and insert the word dimension-;

line 42 delete from the word "of" down to line 45 ending with the word"positioning Column 14 line 51, correct the spelling of the word "an".

Signed and sealed this 6th day of June 1972.

(SEAL) fittest:

EDWARD M.FLETCHER,JR. ROERT GOTTSCHALK \ttesting Officer Commissioner ofPatents

1. A method of constructing a hologram, comprising the steps of:illuminating an object scene with coherent light to produce anobject-modified wavefront, positioning to intercept the object-modifiedwavefront an elongated hologram detector having a horizontal dImensionmuch greater than its vertical dimension but many times smaller thansaid object scene, processing horizontal components of theobject-modified wavefront independent of and different from its verticalcomponents prior to said wavefront striking said detector, and directingcoherent reference radiation toward said hologram detector forinterference with the processed object-modified wavefront to generateholographic information of said object scene for recordation as ahologram.
 2. The method of constructing a hologram according to claim 1wherein said step of processing the horizontal components of theobject-modified wavefront includes focusing horizontal aspects of theobject scene into the horizontal dimension of the hologram detector. 3.The method according to claim 2 wherein said focusing is accomplished bypositioning cylindrical lenses in said object-modified wavefront betweenthe object scene and the hologram detector.
 4. A method of constructinga hologram according to claim 1 wherein the step of processing thehorizontal component of the object-modified wavefront includesdispersing rays of said wavefront substantially only in horizontalplanes
 5. A method of constructing a holographic movie whereinsuccessive independent holograms are constructed according to the methodof clam 1 along an elongated photosensitive material.
 6. A method ofreconstructing an object scene image from holographic informationrecorded according to the method of claim 1, which includes the stepsof: generating a diffracted light order from said holographicinformation in a manner that allows formation of an orthoscopic image ofthe object scene in real space, forming said real space orthoscopicimage by processing horizontal components of the diffracted light order,and dispersing light rays of said diffracted light order in verticalplanes in a manner to increase the beam spread of the diffracted lightorder in its vertical direction.
 7. A method according to claim 6wherein the step of dispersing said light rays in vertical planesincludes placing within said real space orthoscopic image a lenticularscreen.
 8. In a method of constructing a hologram characterized bydirecting to a hologram detector at a finite angle with each other forinterference thereon both an object-information-carrying light wavefrontand a reference light wavefront, the improvement comprising the stepsof: dispersing said object-information-carrying light wavefront at asurface thereacross substantially only in planes extending horizontallyacross the object information wavefront, and converging saidobject-information-carrying light beam in a horizontal direction onto ahologram-detecting area which has a horizontal dispersion that is atleast several times smaller than the horizontal extent of said surfaceat which said object-information-carrying beam is horizontallydispersed.
 9. The method according to claim 8 wherein the step ofdispersing the object information wavefront includes imparting to saidwavefront a substantially periodic relative phase across said surface ina horizontal direction but substantially without relative phasevariation in a vertical direction thereacross.
 10. The method accordingto claim 8 wherein the step of dispersing saidobject-information-carrying wavefront includes positioning at saidsurface thereacross a refracting interface having periodically recurringpeaks and valleys across a horizontal direction thereof but withoutvariation in a vertical direction.
 11. The method according to claim 8wherein the steps of dispersing and converging said object informationbeam are accomplished by positioning within the path of saidobject-information-carrying light wavefront a lens element shaped by itssurfaces to both converge and disperse said wavefront
 12. The methodaccording to claim 8 wherein the vertical dimension of the hologram ismany times smaller than it horizontal dimension.
 13. A methOd ofreconstructing an image from a hologram constructed according to claim12, comprising the steps of: generating from said hologram a diffractedlight order wavefront dispersing rays of said diffracted light orderwavefront in horizontal planes in a manner to neutralize the codingeffect of such dispersion during construction of the hologram, anddispersing rays of said diffracted light order wavefront in verticalplanes in a manner to expand the vertical beam spread of said diffractedlight order wavefront.
 14. The method of reconstructing an imageaccording to claim 13 wherein the step of dispersing rays in verticalplanes includes placing a dispersion structure across said wavefront ata location where an object image comes to focus in real space, saidstructure accomplishing substantially no dispersion in horizontalplanes.
 15. A method of holographically reconstructing an image of anobject comprising the steps of: illuminating said object with coherentlight to produce an object-modified wavefront, positioning to interceptthe object-modified wavefront a horizontally elongated detector manytimes smaller than said object, positioning in said object-modified beambefore striking said detector data reducing optics which affectsubstantially only the horizontal aspect of the object-modifiedwavefront, directing at said hologram a reference beam to interfere withsaid horizontally data reduced object-modified beam, illuminating saiddetector with a reconstructing light wavefront having a curvature insubstantially the opposite direction of the curvature of said referencebeam, thereby producing an image-carrying diffracted beam, andrepositioning in said diffracted beam an optical system withsubstantially the same characteristics as said data-reducing optics in amanner to produce a pseudoscopic image of said object in real space. 16.A method according to claim 15 wherein the step of positioningdata-reducing optics includes positioning at least one cylindricaloptical surface in said object-modified beam.
 17. A method according toclaim 15 wherein the step of positioning data-reducing optics includespositioning in said object-modified beam a dispersion medium thatscatters light in substantially horizontal directions only.
 18. A methodof constructing a hologram copy of a hologram from which an object imageis reconstructed according to the method of claim 15, comprising thesteps of: positioning in said image-carrying diffracted beam ahorizontally elongated copy detector many times smaller than saidobject, positioning copy-data-reducing optics in said image-carryingdiffracted beam prior to striking said horizontally elongated copydetector, said copy-data-reducing optics affecting substantially onlythe horizontal aspect of the object-modified wavefront, and directingtoward the copy detector a reference beam which is coherent with saidreconstruction radiation beam, thereby to construct a copy of saidhologram capable of reconstructing an orthoscopic image of said object.19. A method of reconstructing an orthoscopic image of said object froma copy hologram constructed according to the method of claim 18,comprising the steps of: illuminating said copy hologram with areconstructing wavefront having a curvature opposite in direction to thecurvature of said copy reference beam, thereby producing an orthoscopicimage-carrying diffracted-light beam, positioning in said orthoscopicimage-carrying diffracted-light beam an optical system havingsubstantially the same characteristics as said copy-data-reducingoptics, thereby producing an orthoscopic image of the object in realspace, and positioning in or near said orthoscopic reconstructed image adispersion medium characterized by a plurality of substantiallycylindrical elements horizontally oriented.
 20. A system of large screenholographic movie projection, comprising, a continuous wave lasergenerating a beam of coherent light, a film transport capable ofadvancing a holographic movie at a uniform speed through said coherentlight beam, thereby to generate an image-carrying-diffracted beam fromthe movie, a cylindrical optical system positioned relative to saidlaser and said film transport to be located in the path of thediffracted beam and characterized by affecting substantially only thehorizontal aspect of said beam, and a dispersion medium positioned to belocated in the path of the diffracted beam and characterized byaffecting substantially only the vertical aspect of said beam.
 21. Asystem according to claim 20 wherein said dispersion medium includes alenticular screen having horizontally elongated cylindrical elements.22. A system according to claim 20 wherein said cylindrical opticalsystem includes a second dispersion medium which effects substantiallyonly the horizontal aspect of said beam.
 23. A system for constructing aholographic movie, comprising, a high-powered pulsed laser forilluminating a large object scene, thereby to generate anobject-modified beam, a film transport which advances between pulses ofsaid laser a photosensitive continuous film material positioned behind ahologram aperture having a horizontal dimension many times its verticaldirection, and a cylindrical lens system positioned to receive theobject-modified beam for data reduction in the horizontal directionindependent of the vertical direction.
 24. A system according to claim23 wherein said cylindrical lens system includes a dispersion medium forscattering rays of said object-modified beam in horizontal planes.
 25. Asystem according to claim 23 which additionally comprises a cylindricallens positioned in said object-modified beam to gather light in thevertical direction.